1. Field of the Invention
The present invention relates to novel imido polymers, and, more especially, to novel heat-curable imido prepolymers comprising siloxane bismaleimide recurring units which exhibit low melt viscosities.
2. Description of the Prior Art
French Patent Application FR-A-2,612,196 describes imido polymers which are prepared by reacting one or more conventional N,N'-bismaleimide(s) of the type described in French Patent FR-A-1,555,564 with one or more aromatic diprimary diamine(s), in the presence of a particular N,N'-bismaleimide comprising a diorganopolysiloxane moiety in its molecular structure and optionally another copolymerizable reactant and/or a catalyst.
With respect to the polyimides prepared according to French Patent FR-A-1,555,564 by heating a conventional N,N'-bismaleimide such as, for example, N,N'-4,4'-diphenylmethanebismaleimide, and an aromatic diamine, it has been established that the addition of an N,N'-bismaleimide comprising a diorganopolysiloxane group to the polymerization recipe permits enhancing the impact strength properties of the ultimate cured polymers.